Agronomic and environmental implications of enhanceds-triazine degradation

Abstract

environmental implications of enhanced s-triazine degradation" (2010 AbstractNovel catabolic pathways enabling rapid detoxification of s-triazine herbicides have been elucidated and detected at a growing number of locations. The genes responsible for s-triazine mineralization, i.e. atzABCDEF and trzNDF, occur in at least four bacterial phyla and are implicated in the development of enhanced degradation in agricultural soils from all continents except Antarctica. Enhanced degradation occurs in at least nine crops and six crop rotation systems that rely on s-triazine herbicides for weed control, and, with the exception of acidic soil conditions and s-triazine application frequency, adaptation of the microbial population is independent of soil physiochemical properties and cultural management practices. From an agronomic perspective, residual weed control could be reduced tenfold in s-triazine-adapted relative to non-adapted soils. From an environmental standpoint, the off-site loss of total s-triazine residues could be overestimated 13-fold in adapted soils if altered persistence estimates and metabolic pathways are not reflected in fate and transport models. Empirical models requiring soil pH and s-triazine use history as input parameters predict atrazine persistence more accurately than historical estimates, thereby allowing practitioners to adjust weed control strategies and model input values when warranted. Published

Sonication Effects on Atrazine Dissipation in Vadose Zone Sediment Slurries

“…The sediments were collected from the depth of 11.3-14.6 m in groundwater area having atrazine in sediments and groundwater [10,25]. As the atrazine exposure increases the density or activity of atrazine-degrading microorganisms [5], a significant portion of atrazine in the slurries appeared to be degraded by inherent sediment microorganisms. Microbial growth increased by atrazine addition in the atrazine-amended sediment slurries compared to non-amended slurries, and ammonium, nitrate, and nitrogen concentrations in the sediments were below the detection limit.…”

“…It and its degradation products are commonly found in the soil and surface water, and they can elute through the subsurface sediments to groundwater [1,2]. Atrazine concentrations can be particularly high in point source pollutions, e.g., in the vicinity of dealerships [3][4][5]. Atrazine has been reported to be an endocrine disrupting compound [6,7].…”

“…Methods for the removal of atrazine from soil, subsurface sediments, and groundwater are needed. Microbes and microbial consortia can degrade and even mineralize atrazine [3,9], though the degradation rate is slow in subsurface sediments [5,10,11].…”

Occurrence, diversity and community structure of culturable atrazine degraders in industrial and agricultural soils exposed to the herbicide in Shandong Province, P.R. China

“…Atrazine was considered moderately persistent in soils; with a half-life estimate of about 2 months [11, 12]. However, atrazine residues and metabolites are detectable in soil for years [11, 13–15] and even decades [16] after the herbicide application.…”

“…Since the mid-nineties of the 20 th century, a rapid degradation of atrazine has been revealed in soils continuously exposed to the herbicide at various geographical locations [15]. The half-life of atrazine in such adapted soils can be as short as 1–3.5 days [17], causing reduced efficacy of weed control.…”